Petee brown



(No Model.)

P. BROWN.

DENTAL ENGINE MOTIVE GEAR.

No. 431,026. Patented June 24, 1890.

UNITED STATES PATENT OFFICE.

PETER BROWN, OF MONTREAL, QUEBEC, CANADA.

DENTAL-ENGINE-MOTIVE GEAR.

SPECIFICATION forming part of Letters Patent No. 431,020, dated June 24, 1890.

Application filed May 5, 1890. Serial No. 350,630. (No model.)

To all whom it may concern.-

Be it known that I, PETER BROWN, of the city of Montreal, in the District of` Montreal and Province of Quebec, Canada, have in-v vented certain new and useful Improvements in Dental-Engine Motive Gear; andI do hereby declare that. the following is a full, clear, and exact description of the same.

The invention relates to dental engines generally, its object being to secure instantaneous reverse action of the rotating burr, different speeds of rotation, or the immediate stoppage of same when desired.

Briefly speaking, the improvements cousist in the addition to the engine of an electric motor and switch mechanism, whereby, without stopping or changing the direction of rotation of such motor, an immediate stoppage, a variation oi' speed, or instant reverse action of the rotating burr can be secured.

For full comprehension, however, of the invention, reference must be had to the annexed drawings, forming part of this specification, in which similar letters of reference indicate like parts, and wherein- Figure l is a front view of the lower portion of a foot-power dental engine, with the addition of an electric motor and switch 'mechanism according to my invention; Fig.

2, a plan view of same; Fig. 3, a vertical section on line Fig. 2; and Fig. 4, a plan view of part of such switch mechanism.

A is the standard of the dent-al engine rising from a base B, which has added to it the stand portion B', to accommodate the electric motor O of the O and O or any other type suitable for this kind of work, and adapted to be run from any desired source of electrical supplysuch as a battery-as indicated at D, or a branch from an incandescent-light circuit.

E is the band-wheel of the engine carriedy by the standard A, and F the usual foottreadle for operating the same through suitable connecting-rod, crank, &c.`

The motor C is placed toward the rear of the stand B', and on the forward end of its armature-shaft O' is secured a disk O2 to rotate with it. Transversely to the armatureshaft O' and in front of the disk O2 a shaftG is carried in standards g g from the stand B',

and on this shaft is keyed, at the end nearest the band-wheel E of the engine, agrooved pulley H. A friction-wheel I is mounted on the shaft G and adapted to be shifted along the same, the connection between them being secured by feather and groove or like means. A slot h is formed in the stand beneath the shaft G and parallel with it, and in this is arranged to slide a forked block J, whose forks j engage the hub of the friction-wheel I and serve to move it to right or left, according to the movement it (the block) receives from a toggle-connection formed by two bars K K', pivoted, respectively, to the forked block J and stand B' at a point beneath the friction-wheel I and to each other, as shown in Fig. 4, the toggle being in turn operated by pitman-connections L L', extending from the toe of a treadle M, as shown in Figs. 2 and 3. The head portion L' (as it may be called) of the pitman-connection slides in a groove l in the stand, and has a pin L2 projecting up from its forward end to fit a slot k in the toggle-bar K'.

The heels of the respective treadles are hinged, preferably, to a single shaft N, carried centrally by the front foot B2 of the engine-base and at either end by two ioonblocks B B4.

A coiled spring O is arranged between the treadle M and the floor to keep such treadle normally elevated, as shown by dotted lines in Fig. 3, for a purpose to be presently mentioned.

A binding-post P is formed on the ioorblock B4, that supports the end of the shaft N, near which treadle M is hinged, and arr other binding-post P2 is formed on a plate P', carrying a spring-strip Q, with which the treadle M makes contact when depressed.

As there is a metallic connection between the treadle M and the binding-post P, to which one end of the circuit-wire is attached, such treadle forms one terminal, and the spring contact strip Q, to which the opposite end of the circuit-Wire is taken, the other terminal of the motor-circuit.

A toothed rack R, curved to correspond with the arc of movement of the treadle M, projects upward from the foot B'2 of the engine-base, and a spring-bolt S, carried on the ICO under side of the treadle, is adapted to normally engage with such rack and be disenf gaged therefrom by a sideward movement of the foot against a plate S on the outer end of Such bolt.

During the operation of the dental engine by foot-power, which may sometimes be required to take the place of the electric inotor, the band or cord T is taken round the wheel E; but while the motor is being used it is in place on the pulley Il, as indicated by dotted lines, Fig. l. So long as the treadle M is in the elevated position shown by dotted lines in Fig. 3, it is out of contact with the terminal strip Q, and so keeps the motor-circuit open, while it is only necessary to depress the treadle a notch of rack R to close the circuit and start the motor, which will then run continuously, but in one direction only. In orlder that this rotating action of the motor can be transmitted to the burr of the engine alternately in opposite directions, the frictionwheel l, as before mentioned, is adapted to be shifted along the shaft G, and so make contact with the face of the disk at either side near its periphery, the downward motion of the treadle serving to throw the wheel I tothe right and the upward motion to throw it to the left.

A half-way movement, which brings the wheel l opposite the center of the disk, or an extreme right or left throw out of contact with the same, would serve to secure the immediate stoppage of the wheel, and it will easily be seen that a slower or faster speed can be attained by arranging the point of contact nearer to or farther from the center of the disk.

It will be quite apparent that the mechanism pertaining to my invention can be arranged in portable form and attachable to foot-power engines now in use; and, furthermore, that numerous modifications in the form of the connections between the treadle and the sliding block for moving the frictionwheel along its shaft be used, or a sideward oscillating treadle might be used (27. e., one having a vertical pivot at the heel,) the toe of which would be connected with the block J simply by a projecting pin or finger, and the electrical contacts, termin als, and the rack mechanism be arranged beneath the treadle.

Vhat l claim is as follows:

l. The combination, with a dental engine or the like, of an electric motor and connections, a disk on the armature-shaft of the same, a counter-shaft suitably carried, an adjustable friction-wheel mounted on such shaft and adapted to be shifted along the same, so as to make contact with said disk at various points, and a treadle with connections for adjusting said friction-wheel, as specified.

2. The combination, with the dental engine, of the electric motor C and connections, disk C2 on the armature-shaft of the same, counter-shaft G, suitably carried, adjustable friction-wheel I, treadlc M, and connections between said treadle and friction-wheel for imparting lateral movement to the latter, as set forth.

PETER BROXV N.

Witnesses:

WILL. P. MCFEAT, FRED. S. SEARS. 

